An easily transportable playyard of a simplified structure having upper and lower frame structure and a hub system, which is easily erectable and collapsible without re-assembly or disassembly of any parts is described in U.S. Pat. No. 5,819,342, the entire disclosures of which are incorporated herein by reference.
In the '342 patent, the lower frame assembly includes a hub, a plurality of corner leg connecting members and a plurality of hub legs, one end portion of each hub legs is pivotally coupled to the hub and the other end of each of the hub legs is pivotally coupled to one of the corner leg connecting members. The hub includes a hub body for pivotally coupling to one end portion of at least one leg, a locking member on the hub body, an engaging portion on at least one leg and adjacent to the locking member for cooperating with the locking member. FIG. 2 in the '342 patent depicts that the hub system is composed of a number of complicated configuration components and thus has a relatively high manufacturing cost. In addition, the bottom of the playyard disclosed in the '342 patent is supported only by the hub legs which are unable to provide sufficient support to the bottom of the playyard.